Insulation



Sept- 4, 1962 G. sTRAssER 3,052,019

INSULATION Filed June lO, 1960 CONDUC' 771/5 COA 7'/ MVL/1R C OVE/EAaln/rss PAD /4 U POWDER INVENTOR.

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United States Patent O 3,052,019 INSULATION Gabor Strasser, Bualo, N.Y.,assignor to Bell Aerospace Corporation Filed June 10, 1960, Ser. No.35,307 7 Claims. (Cl. 29-424) This invention relates to the method ofmaking heat insulating structures of the type including, but not limitedto, panels, blankets, walls, housings, and the like. Such insulatingstructures may be suitable for both very low temperature and very hightemperature uses, for example in connection with the storage andhandling of extremely cold liquids such as liquiiied gases, and thestorage and h-andling of molten metals and the like, or as heatinsulating panels for insertion within dual walled aircraft orspacecraft structures, or the like.

It is known that gas-evacuated insulating panels comprisingnon-compacted mixures of carrier powders having dispersed throughoutp-articles lcapable of scattering and/or reflecting and/or absorbingand/or re-radiating radiant energy, operate effectively as highperformance type insulators; and the present invention has to do withthe problem of facilitating the effective packaging of such insulativemixtures into the form of easily handled modules for mounting inassemblies to be insulated to provide the required heat transferbarriers.

More specifically, it is one object of the present invention to providean improved method for packaging a mass of heat insulative material intoa prescribed shape and dimensional form, to thereby render itform-sustaining and to facilitate subsequent assembly thereof into aheat insulative barrier system.

Another object of the invention is to provide a method as aforesaidwhich includes cert-ain gas-evacuating and module surface treatingsteps, thereby rendering the iinished product of improved heatinsulative characteris-tics.

Other objects and advantages of the invention will appear from thespecification hereinafter, by reference to the drawings herewithwherein:

FIG. l is a top plan view of an insulation panel of the presentinvention, with a portion of the top cover structure thereof partiallybroken -away to illustrate the construction thereof;

FIG. 2 is a fragmentary section, on an enlarged scale, taken along linesII-II of FIG. l;

FIG. 3 is a fragmentary diagrammatic illustration of a portion of FIG.2, depicting the preferred thickness variations of the external metalplating applied -to the structure, as will be explained hereinafter; and

FIG. 4 is a greatly enlarged fragmentary sectional illustration showingthe structural fabrication of the article of the invention.

As explained hereinabove, this invention contemplates use of anypreferred type of filler material for the insula-tive modules to befabricated. Typically, such materials may be selected from the naturalor synthetic ceramics; natural or synthetic fibers; or other heatabsorbing or scattering or reflecting particle; or mix-tures thereofhaving suitable heat-resistant, refractory, density, compressivestrength, heat-softening, sintering, and other chemical-physicalcharacteristics that may be required for the given installation. Suchliller materials are usually of pulverant form and are substantiallyfreerunning in the dry state, and the method of the inventioncontemplates that this dry pulverant material will fist be mixed with asuitalble wetting agent, such as naphthalene or the like, so as torender it capable of assuming a cake-like form. Thus, the lillermaterial may now be either packed into a previously fabricated plasticbag designed to inate to the prescribed shape and dimen- 3,652,019Patented Sept. 4, 1962 sions of the insulation module to be made; or,alternatively, the plasticized filler material may be molded into thedesired form and then sprayed with a liquid plastic `of a type adaptedto set up so as to then provide a plastic casing enclosing the fillermaterial and subsequently maintaining it in lthe preformed shapethereof.

In any case, the method of the invention contemplates inclusion of gasvent devices incidental to fabrication of the plastic container for thefiller material. Thus, for example, as shown in FIGS. l and 2 of thedrawing herewith, the filler cake of plasticized filler material asindicated at 10, will be encased within a plastic container such as maybe provided by spraying liquid Mylar or the like thereover to form anencloseing layer of plastic material as indicated at 12. As shown inFIG. 4, prior to spraying the Mylar in place, one or more layers offiberglass fabric 14 may be iirst applied to the surfaces of the fillercake, whereby when the Mylar or other plastic material is sprayedthereon it will coat and partially penetrate the pores of the fiberglassmats so as to provide a structurally reinforced integral casing.

As shown in FIGS. 13, evacuation conduits are arranged at suitableintervals over ythe span of the module to provide vent openingscommunicating with the interior of the container; the conduits beingillustrated herein at 16 and having base plates 1S preferably anchoredinto the filler cake material by means of barbed legs 20` to stabilizethe vent conduits relative to the module upon completion of the device.As indicated at 22, the module may be provided at suitably spacedintervals with internal brace devices 22 formed by including suitablesleeve portions in the plastic bag if a preformed plastic bag is used.Alternatively, if the iiller cake is first formed and then sprayed withplastic, the internal reinforcements may be provided by punchingsuitable openings through the plasticized cake 10, prior to spraying thelatter with liquid plastic as explained hereinabove. In either case thecollar devices 22 extending through the module will function torelatively brace the opposite faces of the module shell, and may also beused to receive fastening devices for mounting the module againstvertical wall surfaces or the like, if desired.

To complete the fabrication of the module of the present invention, thepreshaped cake and casing combination is next subjected to a metalplating operation. This may be performed for example by first coatingthe plastic bag with a suitable paint-like substance to provide anelectrically conductive coating over all exterior surfaces of the modulecasing. The assembly is then subjected to an electro-forming processwhereby a metallic coating of nickel, or Inconel, or rhodium, or othersuitable metal, depending upon the conditions to be encountered, will bedeposited over all external surfaces of the structure. This metalliccoating need be only a few thousandths of an inch thick, and willthereupon function to provide a radiant heat-reflective, weather-proof,stiffening coating over the entire assembly, which in cooperation withthe fiberglass and plastic layers interiorly thereof will provide ashape-sustaining casing for the entire assembly.

As the next step in the process of the present invention, the liquid,such as naphthalene, which was initially used to plasticize the iillermaterial, is evacuated from the structure by suitable heat applicationsthereto; the vent conduit 16 remaining open during this stage of theprocess. Thus, the naphthalene will boil off and will leave the llercake in the form of a foraminous structure of superior heat-reiiectivecharacteristics, and then a partial vacuum may be created within themodule by connecting the vent conduit 16 to a suitable vacuum pump orthe like. When the vacuum reaches the desired level the vent conduits 16may be welded shut, or otherwise closed; and the module is then incondition to be installed for example in an aircraft wall structure orthe like, in association with other similar modules so as to provide thedesired heat transfer barrier.

-It will of course be appreciated that the nature of the ller materialsemployed Will depend upon the service to which the article is to besubjected. Similarly, the precise nature of the plastic casing Will bedetermined by economic as Well as engineering and performanceconsiderations; and the nature of the metallic coating to be platedexteriorly of the plastic case will be determined on the basis ofemissivity characteristics required, manufacturing facilities,economics, as well as other engineering considerations. Thus, althoughonly one specic form of the method and article of the invention has beenillustrated and described in detail herewith, it Will -be understoodthat various changes may be made therein Without departing from thespirit of the invention or the scope of the appended claims.

I claim:

1. A method for fabrication of a heat-insulative module to a prescribedform comprising, mixing a liquid into a mass of pulverant heatinsulation material to render the latter plastic and temporarilyform-retentive, shaping the mass to the form prescribed for the module,encasing the formed mass in an envelope of plastic material,metal-coating the casing of plastic material, venting the interior ofthe casing While heating the contents to volatilize said liquid,applying a vacuum source to the interior of said casing, and thenpressure-sealing the casing to provide an evacuated shape-sustainingmodule for heat insulation purposes.

2. A method for fabrication of a heat-insulative module to a prescribedform comprising, mixing a liquid into a mass of pulverant heatinsulation material to render the latter plastic and temporarilyform-retentive, shaping the mass to the form prescribed for the module,spraying the formed mass with a settable plastic material to form anenvelope thereon, metal-coating the casing of plastic material, ventingthe interior of the casing While heating the contents to volatilize saidliquid, applying a vacuum source to the interior of said casing, andthen pressuresealing the casing to provide an evacuatedshape-sustainingr module for heat insulation purposes.

3. A method for fabrication of a heat-insulative module to a prescribedform comprising, mixing a liquid into a mass of pulverant heatinsulation material to render the latter plastic and temporarilyform-retentive, shaping the mass to the form prescribed for the module,spraying the formed mass with plastic material to encase the mass,thinly metal-coating the casing of plastic material, venting theinterior of the casing while heating the contents to volatilize saidliquid, applying a vacuum source to the interior, and thenpressure-sealing the casing to provide an evacuated shape-sustainingmodule for -heat insulation purposes.

4. A method for fabrication of a heat-insulative module to a prescribed4form comprising, rendering a mass of pulverant heat insulation materialtemporarily plastic and form-retentive, shaping the mass to the formprescribed for the module, spraying a settable flexible material on theformed mass to encase the latter, metalcoating said casing, venting theinterior of the casing While heating the contents to volatilize saidliquid, applying a vacuum source to the interior, and thenpressuresealing the casing to provide an evacuated shape-sustainingmodule for heat insulation purposes.

5. The method of fabricating a heat-insulative module,

which comprises (a) plasticizing a mass of pulverant heat-insulativematerial by combining and mixing a volatile liquid binder and the massof pulverant heat-insulative material (b) in such proportions as torender the mixture shape-retentive,

(c) shaping a quantity of the mixture to a prescribed shape andtemporarily supporting casing-forming means, initially incapable ofshape retention, in intimate contact With and upon the shaped externalsurface of the material during such time as the material is stillplastic and shape-retentive,

(d) rigidifying the casing-forming means to such extent as to be capableof sustaining the aforesaid prescribed shape in the absence of saidbinder,

(e) and thereafter venting the casing and volatilizing said liquid toremove the binder from the mixture and thereby leave substantially onlythe pulverant heat-insulative material within the shape-sustainingcasing.

6. The method of fabricating a heat-insulative module,

which comprises (a) combining and mixing a volatile liquid binder and amass of pulverant heat-insulative material (b) in such proportions astov render the mixture shape-retentive,

(c) shaping a quantity of the mixture to form a cake of prescribedshape,

(d) coating the cake with hardenable plastic material while the cake istemporarily shape-retentive,

(e) metal coating the plastic material, after hardening, to form Withthe hardened plastic material a casing suiciently rigidified as tosustain the prescribed shape in the absence of said binder,

(f) and thereafter venting the casing and volatilizing said liquid toremove the binder from the mixture and thereby leave substantially onlythe pulverant heat-insulative material within the shape-sustainingcasing.

7. The method according to claim 5 wherein (a) the casing is formed inpart by a flexible plastic bag Within which the mixture is placed andshaped,

(b) the casing being rigidified by the application of a metal coating tothe plastic bag.

References Cited in the file of this patent UNITED STATES PATENTS1,934,383 Stafford Nov. 7, 1933 1,942,162 Campbell Ian. 2, 19342,128,336 Torstensson Aug. 30, 1938 2,439,137 Keller Apr. 6, 19482,780,090 Rasmussen Feb. 5, 1957 2,811,408 Braley Oct. 29, 19572,850,890 Rubenstein Sept. 9, 1958 2,878,666 Drummond Mar. 24, 19592,934,399 Morse Apr. 26, 1960

